U.S. patent number 6,242,846 [Application Number 09/248,003] was granted by the patent office on 2001-06-05 for vibration actuator to control pitching vibration.
This patent grant is currently assigned to Nikon Corporation. Invention is credited to Takatoshi Ashizawa, Tsuyoshi Matsumoto, Mitsuhiro Okazaki, Kazuyasu Oone.
United States Patent |
6,242,846 |
Ashizawa , et al. |
June 5, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Vibration actuator to control pitching vibration
Abstract
An ultrasonic actuator to suppress or eliminate pitching
vibration arising in a vibration element when driving the
ultrasonic actuator and to increase driving efficiency and reduce
noise. The ultrasonic actuator includes a vibration element; an
electromechanical conversion element mounted on the vibration
element to generate a drive force in the vibration element by
excitation of the electromechanical conversion element; drive force
output members to extract a drive force obtained by excitation of
the electromechanical conversion element; a relative motion member
in contact with the drive force output members and driven in
relative motion with respect to the vibration element by the drive
force; a base member; and a fixed member to fix the vibration
element to the base member. The vibration element generates, by
excitation of the electromechanical conversion element, a first
vibration in a first direction, and a second vibration in a second
direction different from the first direction, and the fixed member
is located in at least two (2) positions along the vibration
direction of the first vibration and includes a first restriction
member to restrict the vibration element in a vibration direction
of the first vibration, and a second restriction member to restrict
the vibration element in a vibration direction of the second
vibration.
Inventors: |
Ashizawa; Takatoshi (Yokohama,
JP), Matsumoto; Tsuyoshi (Tokyo, JP),
Okazaki; Mitsuhiro (Soka, JP), Oone; Kazuyasu
(Urawa, JP) |
Assignee: |
Nikon Corporation (Tokyo,
JP)
|
Family
ID: |
27286266 |
Appl.
No.: |
09/248,003 |
Filed: |
February 10, 1999 |
Foreign Application Priority Data
|
|
|
|
|
Feb 10, 1998 [JP] |
|
|
10-028623 |
Jun 3, 1998 [JP] |
|
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10-154847 |
Dec 28, 1998 [JP] |
|
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10-372319 |
|
Current U.S.
Class: |
310/323.02;
310/328 |
Current CPC
Class: |
H01L
41/0906 (20130101); H02N 2/103 (20130101); H02N
2/006 (20130101); H02N 2/026 (20130101); H02N
2/004 (20130101); H02N 2/0055 (20130101) |
Current International
Class: |
H01L
41/09 (20060101); H02N 002/00 () |
Field of
Search: |
;310/323.01,323.02,326.16,328 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
63-277477 |
|
Nov 1988 |
|
JP |
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7-143770 |
|
Jun 1995 |
|
JP |
|
8-140374 |
|
May 1996 |
|
JP |
|
Other References
Ultrasonic Motors, Theory and Applications, "Rectangular Plate
Motors", .sctn.4.5, pp. 131-135 and "Linear Motors" .sctn.5.3.6.,
pp. 191-196, by S. Ueha, et al., Oxford University Press, New,
York, New York, Dec. 1993.* .
"Piezoelectric Linear Motors for Moving Optical Pick-up", Y.
Tomikawa, et al., 5th Symposium on Dynamics Related to
Electromagnetic Force, Collected Papers: Joint Auspices of Japan
Mechanical Society, Electrical Society, and Japan AEM Society, Jun.
9-11, 1993, Hitachi City, Japan, pp. 393-398. (English translation
attached).* .
U.S. application No. 08/377,466, filed Jan. 24, 1995.* .
U.S. application No. 08/554,940, filed Nov. 9, 1995.* .
U.S. application No. 08/377,466, (abandoned Feb. 1998). .
U.S. application No. 08/554,940, Tobe et al., Nikon Corporation,
Tokyo, Japan, filed Jun. 13, 1997 (U.S. Patent 6,091,179)..
|
Primary Examiner: Dougherty; Thomas M.
Claims
What is claimed is:
1. A vibration actuator, comprising:
a vibration element including an electro-mechanical conversion
element and a drive force output portion to output a drive force
obtained by the excitation of the electro-mechanical conversion
element and to cause relative motion between the vibration element
and a relative motion member contacting the drive force output
portion;
a base member; and
a fixed member to fix the vibration element to the base member,
wherein the vibration element generates, by the excitation of the
electro-mechanical conversion element, a first vibration in a first
direction, and a second vibration in a second direction different
from the first direction, and
the fixed member includes a first restriction member to restrict
the vibration element in a vibration direction of the first
vibration, a second restriction member located in at least two
places along the vibration direction of the first vibration to
restrict the vibration element in a vibration direction of the
second vibration, a compression member and a support member,
and
the compression member compresses the vibration element toward the
relative motion member, the support member displaceably supports
the vibration element in a direction in which a compressive force
acts on the relative motion member, the compression member and the
support member are both displaceable in the direction in which the
compressive force acts without mutual interference, the first
restriction member is located in the support member, and the second
restriction member is located in the compression member.
2. A vibration actuator as recited in claim 1, wherein at least one
of the compression member and the support member includes a
movement limiting mechanism to limit the movement of the
compression member in the direction vibration of the first
vibration.
3. A vibration actuator as recited in claim 1, wherein
a contact portion of the second restriction member with the
vibration element restricts the vibration in a vibration direction
of the second vibration and in a direction intersecting the
vibration direction of the first vibration and the vibration
direction of the second vibration.
4. A vibration actuator as recited in claim 1, wherein
the first restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the first vibration,
and
the second restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the second
vibration.
5. A vibration actuator as recited in claim 1, wherein
the first restriction member is relatively movable with respect to
the vibration element in the direction of vibration of the second
vibration, and
the second restriction member is relatively movable with respect to
the vibration element in the vibration direction of the first
vibration.
6. A vibration actuator as recited in claim 1, wherein
at least a contact portion of the second restriction member with
the vibration element comprises at least one material selected from
methacrylic resin, phenolic resin, polyamide resin, fluoro resin,
polyacetal resin, acrylonitrile-butadiene-styrene resin, polyimide
resin, polyethylene resin, PVC, polycarbonate resin, polypropylene
resin, polystyrene resin, and epoxy resin.
7. A vibration actuator as recited in claim 4, wherein
the drive force output portion is located along the first vibration
direction of the vibration element, and
the second restriction member couples to the vibration element at a
position with respect to the first vibration direction closer to an
end side of the vibration element than the drive force output
portion.
8. A vibration actuator as recited in claim 7, wherein
the drive force output portion is located at an antinode position
or in a neighborhood of the antinode position of the second
vibration, with respect to the first vibration direction.
9. A vibration actuator as recited in claim 7, wherein
the coupling position is at a node position or in the neighborhood
of the node position of the second vibration.
10. A vibration actuator, comprising:
a vibration element including an electro-mechanical conversion
element and a drive force output portion to output a drive force
obtained by the excitation of the eletro-mechanical conversion
element and to cause relative motion between the vibration element
and a relative motion member contacting the drive force output
portion;
a base member; and
a fixed member to fix the vibration element to the base member,
wherein the vibration element generates, by the excitation of the
electro-mechanical conversion element, a first vibration in a first
direction, and a second vibration in a second direction different
from the first direction, and
the fixed member includes a first restriction member to restrict
the vibration element in a vibration direction of the first
vibration, a second restriction member located in at least two
places along the vibration direction of the first vibration to
restrict the vibration element in a vibration direction of the
second vibration, and a compression support member which is
displaceably supported in a direction of a force acting to compress
the vibration element toward the relative motion member, and
the first restriction member and the second restriction member are
located in the compression support member.
11. A vibration actuator as recited in claim 10, wherein
the first restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the first vibration,
and
the second restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the second
vibration.
12. A vibration actuator as recited in claim 10, wherein
at least a contact portion of the second restriction member with
the vibration element comprises at least one material selected from
methacrylic resin, phenolic resin, polyamide resin, fluoro resin,
polyacetal resin, acrylonitrile-butadiene-styrene resin, polyimide
resin, polyethylene resin, PVC, polycarbonate resin, polypropylene
resin, polystyrene resin, and epoxy resin.
13. A vibration actuator as recited in claim 11, wherein
the drive force output portion is located along the first vibration
direction of the vibration element, and
the second restriction member couples to the vibration element at a
position with respect to the first vibration direction closer to an
end side of the vibration element than the drive force output
portion.
14. A vibration actuator as recited in claim 13, wherein
the drive force output portion is located at an antinode position
or in a neighborhood of the antinode position of the second
vibration, with respect to the first vibration direction.
15. A vibration actuator as recited in claim 13, wherein
the coupling position is at a node position or in the neighborhood
of the node position of the second vibration.
16. A vibration actuator, comprising:
a vibration element including an electro-mechanical conversion
element and a drive force output portion to output a drive force
obtained by the excitation of the electro-mechanical conversion
element and to cause relative motion between the vibration element
and a relative motion member contacting the drive force output
portion;
a base member; and
a fixed member to fix the vibration element to the base member,
wherein the vibration element generates, by the excitation of the
electro-mechanical conversion element, a first vibration in a first
direction, and a second vibration in a second direction different
from the first direction, and
the fixed member includes a first restriction member to restrict
the vibration element in a vibration direction of the first
vibration, a second restriction member located in at least two
places along the vibration direction of the first vibration to
restrict the vibration element in a vibration direction of the
second vibration, and a first compression force generating member
to press the second restriction member to the vibration element to
produce contact between the vibration element and the relative
motion member with a predetermined compressive force.
17. A vibration actuator as recited in claim 16, wherein
the first restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the first vibration,
and
the second restriction member couples to the vibration element in a
position of, or a neighborhood of, a node of the second
vibration.
18. A vibration actuator as recited in claim 16, wherein
at least a contact portion of the second restriction member with
the vibration element comprises at least one material selected from
methacrylic resin, phenolic resin, polyamide resin, fluoro resin,
polyacetal resin, acrylonitrile-butadiene-styrene resin, polyimide
resin, polyethylene resin, PVC, polycarbonate resin, polypropylene
resin, polystyrene resin, and epoxy resin.
19. A vibration actuator as recited in claim 16, further
comprising:
a second compression force generating member, located with respect
to the vibration element on a side opposite to the side where the
first compression force generating member is located, to press the
vibration element on the second restriction member.
20. A vibration actuator as recited in claim 17, wherein
the drive force output portion is located along the first vibration
direction of the vibration element, and
the second restriction member couples to the vibration element at a
position with respect to the first vibration direction closer to an
end side of the vibration element than the drive force output
portion.
21. A vibration actuator as recited in claim 20, wherein
the drive force output portion is located at an antinode position
or in a neighborhood of the antinode position of the second
vibration, with respect to the first vibration direction.
22. A vibration actuator as recited in claim 20, wherein
the coupling position is at a node position or in the neighborhood
of the node position of the second vibration.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority of Japanese
Patent Applications No. 10-028623 filed Feb. 10, 1998, 10-154847
filed Jun. 3, 1998 and 10-372319 filed Dec. 28, 1998, the contents
being incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration actuator having a
vibration element to generate vibration, and to generate relative
motion between the vibration element and a relative motion member
in compressive contact with the vibration element. More
particularly, the present invention relates to an ultrasonic
actuator having restriction members to regulate pitching vibration,
and a method of producing the vibration actuator.
2. Description of the Related Art
Vibration actuators which generate vibrations in the ultrasonic
regions are known as ultrasonic actuators or ultrasonic motors. A
conventional vibration actuator using two simultaneously generated
degenerate modes of vibration having different form is disclosed,
for example, in "Fifth Collected Papers, Fifth Dynamics Symposium
Related to Electromagnetic Force", page 393, Tomikawa (hereinafter
"Tomikawa").
FIG. 22 is a perspective diagram of a vibration actuator 1 having a
vibration element 2 disclosed by Tomikawa. Moreover, FIG. 23 is
diagram illustrating a side view of the vibration element 2 and an
example of a waveform of two (2) vibrations L1, B4 generated in the
vibration element 2. As shown in FIG. 22, the vibration element 2
includes an elastic member 3 and an electromechanical energy
converter (referred to hereinbelow as a "piezoelectric member")
which converts electrical energy into mechanical energy. The
elastic member 3 has a rectangular plate form and is a metallic
material having a large resonant sharpness. The piezoelectric
member 4 is mounted on one flat side of the elastic member 3.
Moreover, two drive force output members 3a, 3b are formed
protruding on a flat side of the elastic member 3 opposite the side
on which the piezoelectric member 4 is mounted.
As shown in FIG. 22, the piezoelectric member 4 includes four (4)
connected regions: input regions 4a, 4b to which two (2) phases A
and B of drive voltage V.sub.A, V.sub.B are respectively applied; a
detection region 4p which monitors the vibration state of the
vibration element 2, and a ground region 4g. Silver electrodes 5a,
5b, 5p and 5g, for example, are mutually separately mounted on
respective regions 4a, 4b, 4p, 4g.
Sliding members, (not shown in the drawing) formed of a high
molecular material as a main component are affixed to the bottom
surface of the drive force output members 3a, 3b. A relative motion
member 6 is caused to be in compressive contact with the elastic
member 3 via the sliding members by a suitable compressive
force.
Moreover, the dimensions of the elastic member 3 are set such that
the frequencies of the first order longitudinal vibration L1 and
the fourth order bending vibration B4 about coincide. Furthermore,
the drive force output members 3a, 3b are arranged in the length
direction of the vibration element 2 in positions coinciding with
the outside antinode positions l1, l4, among four (4) antinode
positions l1, l2, l3 and l4 of the bending vibration B4.
As shown in FIG. 23, when high frequency drive voltages V.sub.A,
V.sub.B with a .pi./2 phase displacement are applied to the elastic
member 3, a first order longitudinal vibration L1, which vibrates
in the length direction of the vibration element 2, and a fourth
order bending vibration B4, which vibrates in the thickness
direction of the vibration element 2, are simultaneously generated.
The longitudinal vibration L1 and the bending vibration B4
generated in the elastic member 3 are combined, and the respective
bottom surfaces of the drive force output members 3a, 3b are
periodically displaced in elliptical form to generate an elliptical
motion. As described above, the vibration element 2 generates
relative motion between the drive force output members 3a, 3b and
the relative motion member 6.
In the above-described manner, in a vibration actuator including
the vibration element 2 having different modes of degenerate form,
the longitudinal vibration L1 and bending vibration B4 generated in
the elastic member 3 combine to generate elliptical motion in the
drive force output members 3a, 3b, and to generate relative motion
between the drive force output members 3a, 3b and the relative
motion member 6. Accordingly, in the conventional actuator 1, it is
necessary for the vibration element 2 and the relative motion
member 6 to be placed in compressive contact by a suitable
compressive force.
To apply a suitable compressive force, the present Applicant has
proposed a compression member which compresses the vibration
element 2 toward the relative motion member 6 at one position in
the center portion with respect to the length direction of the
vibration element 2 (the compression position C shown in FIGS. 22
and 23), as disclosed, for example, in Japanese Laid-Open Patent
Publication JP-A-H8-140374.
Using the compression member disclosed in JP-A-H8-140374, the
vibration element 2 can be reliably compressed toward the relative
motion member 6 with a suitable compressive force, and with a very
simple structure. Further, the compression member enables the
elliptical motion generated in the vibration element 2 to be
efficiently propagated to the relative motion member 6.
Moreover, as shown in FIG. 23, because the compression position C
corresponds to the respective nodal positions of the longitudinal
vibration L1 and the bending vibration B4 which arise in the
elastic member 3, the vibrational attenuation accompanying the
compression can be suppressed as much as possible. Because of this,
the compression position C shown in FIGS. 22 and 23 was previously
considered to be the most preferable position in order to design a
vibration actuator which controls the vibrational attenuation
accompanying compression, and performs reliable compression.
Furthermore, heretofore, it was considered that reliable driving of
the vibration actuator 1 was possible by compressing the vibration
element 2 toward the relative motion member 6 at the compression
position C shown in FIG. 23.
However, upon investigation by the present inventors, it was
ascertained that by performing compression at the compression
position C accompanying the driving of the vibration element 2, the
two end portions in the length direction of the vibration element 2
vibrate, rising and falling in mutually opposite directions,
centered on the compression position C. More specifically, the
present inventors discovered that a pitching vibration may arise in
the vibration element 2. One example of a direction of the pitching
vibration is shown by the arrows in FIG. 23.
When the pitching vibration arises in the vibration element 2,
noise having the frequency of the pitching vibration is generated,
and the silentness, which is a characteristic feature of the
vibration actuator, is lost. Moreover, a function (referred to
hereinbelow as a "clutch function"), which is continuously
propagated to the relative motion member 6 by the longitudinal
vibration L1 and bending vibration B4 which arise in the vibration
element 2, becomes insufficient, and driving efficiency falls.
Moreover, because the conventional vibration actuator does not
include means to control the pitching vibration, the pitching
vibration continues to be generated.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vibration
actuator which solves the above-described problems of the
conventional vibration actuator discovered by the present
inventors.
It is another object of the present invention to provide a
vibration actuator which controls pitching vibration, prevents the
generation of noise and the decrease in drive efficiency
accompanying pitching vibration, and provides increased
performance.
As a result of diligent research by the present inventors, it was
determined that while the conventional vibration element 2 is
compressed at one compression position C to transmit a compressive
force to the relative motion member 6, a compression force is
generated in the thickness direction of the relative motion member
6 by the bending vibration B4. A couple, which is a pair of
parallel forces having equal magnitude and opposite direction, is
then generated about the compression position C, by the reaction of
the compression force, and of the couple the vibration element 2
acquires a pitching vibration with the compression position C as
its center as a result of the couple.
Consequently, the present inventors conducted further
investigations, and the following three points were determined with
respect to a vibration actuator including a vibration element which
generates a longitudinal vibration and a bending vibration.
(1) The couple acting on the vibration element can be reliably
controlled, and the generation of noise and the reduction of clutch
function can be prevented, with first restriction member to
restrict the vibration element in the vibration direction of the
longitudinal vibration, and at at least two (2) places which relate
to the direction of the longitudinal vibration, using a second
restriction member which restricts the vibration element in the
direction of the bending vibration.
(2) The vibration element can be reliably supported without play,
and the generation of noise can be controlled, by arranging the
first and second restriction members mutually independently in
separate members, and by contriving the form of the respective
members.
(3) The couple can be more reliably controlled by coupling the
second restriction member to the vibration element closer to the
vibration element ends than plural drive force output members
disposed in the vibration element along the direction of relative
motion.
Objects and advantages of the present invention are achieved in
accordance with embodiments of the present invention with a
vibration actuator comprising a vibration element including an
electromechanical conversion element and a drive force output
portion to output a drive force obtained by the excitation of the
electromechanical conversion element and to cause relative motion
between the vibration element and a relative motion member
contacting the drive force output portion; a base member; and a
fixed member to fix the vibration element to the base member,
wherein the vibration element generates, by excitation of the
electromechanical conversion element, a first vibration in a first
direction, and a second vibration in a second direction different
from the first direction, and the fixed member includes a first
restriction member to restrict the vibration element in a vibration
direction of the first vibration, and a second restriction member
located in at least two (2) positions along the vibration direction
of the first vibration to restrict the vibration element in a
vibration direction of the second vibration.
In accordance with embodiments of the present invention, the first
restriction member is coupled to the vibration element in a
position corresponding to a node of the first vibration, or a
neighborhood of the node of the first vibration, and the second
restriction member is coupled to the vibration element in a
position corresponding to a node of the second vibration, or a
neighborhood of the node of the second vibration.
Moreover, in accordance with embodiments of the invention, the
first restriction member can be fixed to the vibration element.
The fixed member may include a compression member and a support
member, wherein the compression member compresses the vibration
element toward the relative motion member, and the support member
displaceably supports the vibration element with respect to a
direction of a force which compresses the vibration element toward
the relative motion member. The compression member and the support
member may be displaceable with respect to the direction of action
of the compression force, and do not mutually interfere. The first
restriction member may be located in the support member, and also
the second restriction member may be located in the compression
member.
Moreover, at least one of the compression member and support member
may comprise a movement limiting mechanism to limit the movement of
the compression member toward the direction of the first
vibration.
Moreover, a contact portion of the second restriction member with
the vibration element restricts the vibration in a vibration
direction of the second vibration, and in a direction intersecting
the vibration direction of the first vibration, and the vibration
direction of the second vibration.
In accordance with embodiments of the present invention, the first
restriction member may move in relative motion with respect to the
vibration element in the vibration direction of the second
vibration, and the second restriction member may move in relative
motion with respect to the vibration element in the vibration
direction of the first vibration.
Moreover, in accordance with embodiments of the invention, the
fixed member may comprise a compression support member which is
displaceably supported in a direction of the force acting to
compress the vibration element toward the relative motion member.
Further, the first restriction member and the second restriction
member may be located in the compression support member.
In accordance with embodiments of the present invention, the fixed
member may comprise a first compression force generating member
which presses the second restriction member upon the vibration
element to cause contact between the vibration element and the
relative motion member with a predetermined compressive force.
Moreover, in accordance with embodiments of the present invention,
at least a contact portion of the second restriction member with
the vibration element may comprise at least one of methacrylate
resin, phenolic resin, polyamide resin, fluoro-resin, polyacetal
resin, acrylonitrile-butadiene copolymer resin, polyimide resin,
polyethylene resin, polyvinyl acetate, polycarbonate resin,
polypropylene resin, polystyrene resin, and epoxy resin.
Moreover, the vibration actuator may further comprise a second
compression generation member, located on the side opposite the
side where the first compression generation member is located, to
press the vibration element onto the second restriction member.
Moreover, the vibration actuator may further comprise a third
restriction member, located on the side opposite the side where the
second restriction member is located, to restrict the vibration
element with respect to the vibration direction of the second
vibration.
Moreover, in accordance with embodiments of the present invention,
the drive force output portion may be located along the first
vibration direction of the vibration element, and the second
restriction member couples to the vibration element at a position
with respect to the first direction closer to an end side of the
vibration element than the drive force output portion.
In accordance with embodiments of the present invention, the drive
force output portion is located at an antinode position of the
second vibration or in a neighborhood of the antinode position,
with respect to the first vibration direction.
Moreover, in accordance with embodiments of the invention, the
coupling position is at a node position, or in the neighborhood of
the node position of the second vibration.
Objects and advantages of the present invention are achieved in
accordance with another embodiment of the present invention with a
vibration actuator, comprising a vibration element including an
electro-mechanical conversion element and a drive force output
portion to output drive force obtained by the excitation of the
electro-mechanical conversion element, to cause relative motion
between the vibration element and a relative motion member
contacting the drive force output portion; a base member; and a
fixed member to fix the vibration element to the base member,
wherein the vibration element generates, by the excitation of the
electro-mechanical conversion element, a first vibration in a first
direction, and a second vibration in a second direction different
from the first direction, and the fixed member includes a first
restriction member to restrict the vibration element in a vibration
direction of the first vibration, and a second restriction member,
arranged in at least two (2) positions along the vibration
direction of the first vibration, to restrict the vibration element
in a vibration direction of the second vibration, and located on a
mutually opposite side with respect to the vibration element.
In accordance with embodiments of the present invention, one side
of the second restriction member and comes into contact with the
vibration element at a surface on which the drive force output
portion is positioned on the vibration element.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the invention will become
apparent and more readily appreciated from the following
description of the preferred embodiments, taken in conjunction with
the accompanying drawings of which:
FIG. 1A is a diagram illustrating an ultrasonic actuator and an
example of a generated vibration waveform in accordance with a
first embodiment of the present invention.
FIG. 1B is a top view showing a vibration element of the ultrasonic
actuator in accordance with the first embodiment of the present
invention.
FIG. 2 is a perspective view of the ultrasonic actuator in
accordance with the first embodiment of the present invention.
FIG. 3 is a block diagram of drive circuit of the vibration element
of the ultrasonic actuator in accordance with the first embodiment
of the present invention.
FIG. 4A-4D are diagrams illustrating generation of elliptical
motion in a drive force output member by combining a first order
longitudinal vibration and a fourth order bending vibration in the
vibration element in the ultrasonic actuator in accordance with the
first embodiment of the present invention.
FIG. 5 is a diagram illustrating an ultrasonic actuator and an
example of a generated vibration waveform in accordance with a
second embodiment of the present invention.
FIG. 6 is a front view of an ultrasonic actuator in accordance with
a fourth embodiment of the present invention.
FIG. 7 is a cross-sectional diagram of a compression support
mechanism taken along a cross section VI--VI of FIG. 6 in
accordance with the fourth embodiment of the present invention.
FIGS. 8A-8B illustrate a front view and lower surface view,
respectively, of a compression support member in accordance with
the fourth embodiment of the present invention.
FIG. 9A is a diagram illustrating an ultrasonic actuator and an
example of a generated vibration waveform in accordance with a
fifth embodiment of the present invention.
FIG. 9B is a top view showing a vibration element of an ultrasonic
actuator in accordance with the fifth embodiment of the present
invention.
FIG. 10 is a perspective view of the ultrasonic actuator in
accordance with the fifth embodiment of the present invention.
FIG. 11 is a diagram illustrating an ultrasonic actuator and an
example of a generated vibration waveform in accordance with a
sixth embodiment of the present invention.
FIG. 12 is a diagram illustrating an ultrasonic actuator and an
example of a generated vibration waveform in accordance with a
seventh embodiment of the present invention.
FIG. 13 is a partially transparent perspective exploded view of an
ultrasonic actuator in accordance an eighth embodiment of the
present invention.
FIG. 14 is a front view of the ultrasonic actuator in accordance
with the eighth embodiment of the present invention.
FIG. 15 is a partially transparent front view of the ultrasonic
actuator in accordance with the eighth embodiment of the present
invention.
FIG. 16 is a longitudinal sectional view taken in the center of the
ultrasonic actuator in accordance with the eighth embodiment of the
present invention.
FIG. 17 is a top view of a support member in accordance with the
eighth embodiment of the present invention.
FIGS. 18A-18D are a left side view, a front view, a right side view
and a lower surface view, respectively, of a compression member in
accordance with the eighth embodiment of the present invention.
FIG. 19 is a top view of a support member in accordance with a
ninth embodiment of the present invention.
FIGS. 20A-20D are a left side view, a front view, a right side view
and a lower surface view of a compression member in accordance with
the ninth embodiment of the present invention.
FIG. 21 is a partially transparent front view of the ultrasonic
actuator in accordance with a tenth embodiment of the present
invention.
FIG. 22 is a perspective view of a prior art vibration actuator
including a vibration element using degenerate modes of different
form.
FIG. 23 is a diagram illustrating examples of a waveform of two
vibrations generated in the vibration element shown in FIG. 22.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the preferred embodiments
of the present invention, examples of which are illustrated in the
accompanying drawings, wherein like reference numerals refer to
like elements throughout.
Embodiments of a vibration actuator in accordance with the present
invention are described in detail hereinbelow with reference to the
accompanying drawings. Furthermore, the embodiments of the present
invention are described hereinafter with reference to an example of
an ultrasonic actuator using a vibration actuator in the ultrasonic
region of vibration.
First Preferred Embodiment
FIGS. 1A and 1B illustrate an ultrasonic actuator 10 in accordance
with a first embodiment of the present invention. More
particularly, FIG. 1A is a diagram illustrating an ultrasonic
actuator 10 and an example of a generated vibration waveform, and
FIG. 1B is a top view of a vibration element 11 used in the
ultrasonic actuator 10. FIG. 2 is a perspective view of the
ultrasonic actuator 10 in accordance with the first embodiment of
the present invention.
As shown in FIGS. 1 and 2, the ultrasonic actuator 10 in accordance
with the first embodiment of the invention includes a vibration
element 11 to generate a first order longitudinal vibration L1,
which is a first vibration, and a fourth order bending vibration
B4, which is a second vibration; a relative motion member 22; a
compression support mechanism 31; and a casing 41, which houses the
compression support mechanism 31, and through which the relative
motion member 22 passes. These elements are described in more
detail hereinbelow.
The vibration element 11 includes an elastic member 12 and a
piezoelectric member 13 mounted on a flat surface of one side of
the elastic member 12. The elastic member 12 has a rectangular flat
plate form and preferably comprises a metallic material having
large resonant sharpness, such as steel, stainless steel, phosphor
bronze, or Erinvar, etc. Moreover, the dimensions of each portion
of the elastic member 12 are set such that the characteristic
frequencies of the generated first order longitudinal vibration L1
and fourth order bending vibration B4 about coincide.
The piezoelectric member 13 is adhered, for example, to one flat
face of the elastic member 12. Moreover, two (2) grooves separated
by a predetermined distance in the relative motion direction (the
left and right direction in FIG. 1A) are disposed on the other flat
face of the elastic member 12 in the width direction of the elastic
member 12. Sliding members which are rectangular in cross section
and have an angle bar form are fitted and adhered in the grooves.
The sliding members are mounted to project from the elastic member
12 and comprise a high molecular material or the like, such as
PTFE, polyimide resin, PEN, PPS, PEEK, and the like. The sliding
members function as drive force output members 12a, 12b. The
elastic member 12 contacts the relative motion member 22 via the
drive force output members 12a, 12b comprising the sliding
members.
Furthermore, each drive force output member 12a, 12b is divided
into two (2) elements in the width direction of the vibration
element 11, and the two elements are respectively located at the
ends of the width direction of the vibration element 11. In
accordance with the first embodiment of the present invention, the
respective drive force output members 12a, 12b comprise two (2)
sliding members. Accordingly, the vibration element 11 comprises
four (4) sliding members.
As shown in FIG. 1A, the drive force output members 12a, 12b are
disposed in positions coinciding with the outer position antinode
positions l1, l4 among the four (4) antinode positions l1-l4 of the
fourth order bending vibration B4. Furthermore, it is not necessary
to dispose the drive force output members 12a, 12b in positions
accurately coinciding with the antinode positions l1, l4 of the
bending vibration B4. Alternatively, the drive force output members
12a, 12b may be disposed in the neighborhood of the antinode
positions l1, l4.
In accordance with the first embodiment of the present invention,
the piezoelectric member 13 comprises one (1) thin plate
piezoelectric member preferably made of PZT (lead zirconium
titanate). The piezoelectric member 13 includes input regions 13a,
13c to which A phase drive signals are input, and input regions
13b, 13d, to which B phase drive signals are input (about .pi./2
displaced in phase from the A phase). As shown in FIG. 1B, the
input regions 13a-13d are respectively formed connected to four (4)
regions compartmented by five (5) nodal positions n1-n5 of the
bending vibration B4. More particularly, each input region 13a-13d
deforms as a result of the input of drive signals, but none extends
over a respective nodal position n1-n5. Because of this
arrangement, the deformation of the input regions 13a-13d is not
suppressed by the nodal positions n1-n5. Accordingly, the
electrical energy input into each input region 13a-13d is converted
to deformation of the elastic member 12, specifically, converted
into mechanical energy, with maximum effect.
Moreover, detection regions 13p, 13p' are disposed at the nodes n2,
n4 of the bending vibration B4. The detection regions 13p, 13p'
output electrical energy as a result of the longitudinal vibration
L1 generated by the vibration element 11. The vibrational state of
the longitudinal vibration L1 generated by the vibration element 11
is monitored by the detection regions 13p, 13p'.
Each input region 13a-13d and each detection region 13p, 13p' has a
surface covered with a respective silver electrode 15a-15d, 15p,
15p'. Accordingly, each input region 13a-13d independently inputs
drive signals, and each detection region 13p, 13p' can output
independent detection signals.
As shown in FIG. 2, each silver electrode 15a-15d, 15p, 15p' is
respectively connected to a lead wire 16a-16d, 16p, 16p' in order
to perform transfer of electrical energy by respective soldered
portions 17a-17d, 17p, 17p' which bulge out.
Furthermore, in accordance with the first embodiment of the
invention, as shown in FIG. 1B, the vibration element 11 is formed
such that it exhibits point symmetry centered on a center portion
of its flat surface. Accordingly, the elliptical motion generated
in the drive force output members 12a, 12b has about the same form,
and drive error which accompanies a reversal of the direction of
relative motion is about eliminated.
FIG. 3 is a block diagram of a drive circuit of the vibration
element 11 in accordance with the first embodiment of the present
invention. As shown in FIG. 3, an oscillator 18 generates signals
having a frequency corresponding to the longitudinal vibration L1
and bending vibration B4 of the vibration element 11. The output of
the oscillator 18 is branched into two outputs. One output is
amplified by amplifiers 19a, 19c, and the respective outputs of
amplifiers 19a, 19c are input to the silver electrodes 15a, 15c of
the input regions 13a, 13c. The other branched output, after having
its phase displaced by .pi./2 from the A phase voltage by a phase
shifter 20, is input as a B phase drive signal to the silver
electrodes 15b, 15d of the input regions 13b, 13d via the
amplifiers 19b, 19d.
Output voltages from the detection regions 13p, 13p' are input to a
control circuit 21. The control circuit 21 compares the output
voltages with a standard voltage which is previously set, and
controls the amplifier 18 to lower the frequency when the output
from the detection regions 13p, 13p' is smaller than the standard
voltage. On the other hand, the control circuit 21 controls the
amplifier 18 to raise the frequency when the output from the
detection regions 13p, 13p' is larger than the standard voltage.
The vibration amplitude of the vibration element 11 is maintained
at a predetermined magnitude by the control circuit 21.
In the above-described manner, an A phase drive signal having a
frequency at which the characteristic frequencies of the
longitudinal vibration L1 and the bending vibration B4 agree is
input to the input regions 13a, 13c of the piezoelectric member 13.
Moreover, a B phase drive signal having a phase difference of
.pi./2 from the A phase drive signal is input to the input regions
13b, 13d. As a result of the drive signals, as shown in FIG. 1A, a
first order longitudinal vibration L1, which is a first vibration
in the relative motion direction (the left and right direction in
FIG. 1), and a fourth order bending vibration B4 which is a second
vibration in a direction intersecting the direction of relative
motion, are simultaneously generated in the elastic member 12. The
combination of the first order longitudinal vibration L1 and the
fourth order bending vibration B4 generates elliptical motion in
the drive force output members 12a, 12b.
FIGS. 4A-4D are diagrams periodically showing the state of
generation of elliptical motion in the drive force output members
12a, 12b by combining a first order longitudinal vibration L1 and a
fourth order bending vibration B4. Furthermore, in FIGS. 4A-4D, for
convenience, each output region 13a-13d is shown in a mutually
separated state.
In particular, FIG. 4A illustrates the time changes of the two (2)
phase drive signals (drive voltages) A, B for times t1-t9. The
ordinate in FIG. 4A shows the effective value of the high frequency
voltage. FIG. 4B illustrates the deformation of a cross section of
the elastic member 12, and shows the time changes of the bending
vibration B4 (second vibration) generated in the vibration element
11 for the times t1-t9. FIG. 4C illustrates the changes of the
cross section of the elastic member 12, and shows the time changes
of the longitudinal vibration L1 (first vibration) generated in the
vibration element 11 for the times t1-t9. Furthermore, FIG. 4D
illustrates the time changes of the elliptical motion generated in
the drive force output members 12a, 12b of the vibration element 11
for the times t1-t9.
As shown in FIG. 4A, at time t1, the A phase drive signal generates
a positive voltage, and the B phase drive signal generates the same
positive voltage. As shown in FIG. 4B, the bending vibrations due
to the A phase and the B phase drive signal mutually cancel, and
the material points Y1 and Z1 both become zero in amplitude.
Moreover, as shown in FIG. 4C, a longitudinal vibration is
generated in the elastic member 12 in a stretching direction by the
A phase drive signals and B phase drive signals. As shown by the
arrows in FIG. 4C, at time t1, material points Y2, Z2 together show
a maximum extension centered on the nodal position X (the nodal
position n3 in FIG. 1A). As a result, as shown in FIG. 4D, the
longitudinal vibration and the bending vibration are combined, and
the combination of the motion of the material points Y1, Y2
comprises the motion of the material point Y. Moreover, the
combination of the motion of the material points Z1, Z2 comprises
the motion of the material point Z.
As shown in FIG. 4A, at time t2, the A phase drive signal generates
a positive voltage, and the B phase drive signal becomes zero. As
shown in FIG. 4B, a bending vibration is generated by the A phase
drive signal, the material point Y1 displaces in the negative
direction, and the material point Z1 displaces in the positive
direction. Moreover, as shown in FIG. 4C, a longitudinal vibration
is generated by the A phase drive signal, and the material points
Y2 and Z2 contract from their positions at time t1. As a result, as
shown in FIG. 4D, the longitudinal vibration and the bending
vibration are combined, and the material points Y and Z together
rotate counterclockwise from their positions at time t1.
As shown in FIG. 4A, at time t3, the A phase drive signal generates
a positive voltage, and the B phase drive signal generates an equal
but negative voltage. As shown in FIG. 4B, at time t3, a bending
vibration is generated by the A phase drive signal and the B phase
drive signal, combined and amplified, and the material point Y1
displaces more in the negative direction than at time t2. Moreover,
the material point Z1 is amplified more in the positive direction
than at time t2, and exhibits a maximum positive amplitude value.
Moreover, as shown in FIG. 4C, the longitudinal vibrations
generated by the A phase drive signal and the B phase drive signal
mutually cancel, and the material points Y2 and Z2 return to their
initial positions. As a result, as shown in FIG. 4D, the
longitudinal vibration and the bending vibration are combined, and
the material points Y and Z together rotate further
counterclockwise from their positions at time t2.
As shown in FIG. 4A, at time t4, the A phase drive signal becomes
zero, and the B phase drive signal generates a positive voltage. As
shown in FIG. 4B, a bending vibration is generated by the B phase
drive signal, the material point Y1 decreases in amplitude from the
time t3, and the material point Z1 decreases in amplitude from the
time t3. Moreover, as shown in FIG. 4C, a longitudinal vibration is
generated by the B phase drive signal, and the material points Y2
and Z2 contract together. As a result, as shown in FIG. 4D, the
longitudinal vibration and the bending vibration are combined, and
the material points Y and Z together rotate still further
counterclockwise from their positions at time t3.
As shown in FIG. 4A, at time t5, the A phase drive signal generates
a negative voltage, and the B phase drive signal generates the same
negative voltage. As shown in FIG. 4B, the bending vibrations as a
result of the A phase drive signal and the B phase drive signal
mutually cancel, and the material points Y1 and Z1 both become zero
amplitude. Moreover, as shown in FIG. 4C, a longitudinal vibration
is generated in the stretching direction by the A phase drive
signal and B phase drive signal. At time t5, the material points
Y2, Z2 together, as shown by the arrows, show a maximum contraction
centered on the nodal position X (the nodal position n3 in FIG.
1A). As a result, as shown in FIG. 4D, the longitudinal vibration
and the bending vibration are combined, and the material points Y
and Z together rotate counterclockwise from their positions at time
t4.
For times t6-t9 also, longitudinal vibrations and bending
vibrations are generated similarly to times t1-t5, and, as a
result, as shown in FIG. 4D, the material points Y and Z rotate
counterclockwise. In the above-described manner, an elliptical
motion, displaced counterclockwise by a half cycle, is respectively
generated in the vibration element 11 and the drive force output
members 12a, 12b. The relative motion member 22, which is in
compressive contact with the drive force output members 12a, 12b,
is driven in one direction by the generated elliptical motion.
Moreover, to make the relative motion member 22 reverse in its
direction, the B phase drive signal may be set to a phase
difference of -.pi./2 with respect to the A phase drive signal.
As shown in FIG. 1A, the relative motion member 22, which is a
moving member, is located in contact with the drive force output
members 12a, 12b of the vibration element 11. In accordance with
the first embodiment of the present invention, the relative motion
member 22 is formed of a zonal lamina, and is preferably made of
stainless steel. The relative motion member 22 is driven in the
same direction (left to right direction in FIG. 1A) as the
vibration direction of the longitudinal vibration L1 by the
elliptical motion generated in the drive force output members 12a,
12b. Furthermore, the relative motion member 22 may preferably
comprise a copper alloy, aluminum alloy, or furthermore a
macromolecular material, or the like.
The relative motion member 22 is conveyed, guided by conveyor
rollers 23a, 23b in contact with one surface of the relative motion
member 22, and four (4) conveyor rollers (not shown in the drawing)
in contact with both end faces of the width direction of the
relative motion member 22. The conveyor rollers guide the relative
motion member 22 such that it is capable of reciprocating motion in
both of the relative motion directions.
Moreover, the six (6) conveyor rollers, including the conveyor
rollers 23a, 23b, are supported to rotate freely by a casing 41, as
will be described in detail hereinbelow.
As shown in FIG. 1A and in FIG. 2, the compression support
mechanism 31 includes a compression support member 32, which
performs restriction of the vibration element 11, and a first
compression force generating member 33, which urges the vibration
element 11 toward the relative motion member 22. Furthermore, for
convenience of illustration, the compression support mechanism 31
shown in FIG. 2 is partially omitted.
The compression support member 32 and the first compression force
generating member 33 will now be described in more detail
hereinbelow. The compression support member 32 in accordance with
the first embodiment of the invention comprises two (2) restricting
pins 34a, 34b, which operate as a first restriction member, and a
laminar compression support member 35 having two projecting units
36a, 36b, which operate as a second restriction member. The
restricting pins 34a, 34b respectively have one end fixed to a
ceiling surface of the casing 41, described in more detail
hereinafter. The restricting pins 34a, 34b pass through through
holes 37a, 37b disposed in the compression support member 35 in a
state having a gap with respect to the compression support member
35. Semicircular notches 11a, 11b are disposed in the center of the
length direction of the vibration element 11 (node n3 of the first
order longitudinal vibration L1, which is the first vibration
generated in the vibration element 11), into which the restricting
pins 34a, 34b fit. The restricting pins 34a, 34b fit into the
semicircular notches with a loose fit, that is, with a fit having a
clearance. The vibration element 11 is reliably restricted in the
movement direction of the longitudinal vibration L1 by the
restricting pins 34a, 34b. Furthermore, it is not necessary that
the position at which the restricting pins 34a, 34b fit into the
vibration element 11 accurately coincide with the nodal position n3
of the longitudinal vibration L1, which is the first vibration.
Alternatively, the position at which the restricting pins 34a, 34b
fit into the vibration element 11 may be in the neighborhood of the
nodal position n3.
Moreover, as shown in FIG. 1A and in FIG. 2, the compression
support member 35 is located with respect to the vibration element
11 on the side opposite to the side where the relative motion
member 22 is located. Because the through holes 37a, 37b through
which the restricting pins 34a, 34b pass are formed in the
compression support member 35 such that there is a clearance
between the through holes 37a, 37b and the restricting pins 34a,
34b, the compression support member 35 is displaceably supported
with respect to the direction through which the restricting pins
34a, 34b pass. Specifically, compression support member 35 is
displaceably supported in the direction in which the compressive
force compresses the vibration element 11 in the direction of the
relative motion member 22.
Moreover, projecting units 36a, 36b having rectangular form are
disposed on both sides of the compression support member 35 in the
relative motion direction toward the flat surface of the vibration
element 11. The projecting units 36a, 36b are located such that
they contact the vibration element 11 in positions astride the two
nodal positions n2, n4 of the fourth order bending vibration B4
generated in the vibration element 11. In the above-described
manner, the vibration element 11 is reliably restricted with
respect to the vibration direction of the bending vibration B4 by
the projecting units 36a, 36b. Further, the projecting units 36a,
36b are not necessarily disposed at positions which accurately
coincide with the nodal positions n2, n4, and may be in the
neighborhood of the nodal positions n2, n4.
As shown in FIG. 2, the projecting units 36a, 36b are disposed
divided into two (2) with respect to the width direction of the
vibration element 11 in order to avoid interference with the solder
bulges 17a-17d, 17p, 17p'.
In accordance with the first embodiment of the invention, the
restricting pins 34a, 34b, the compression support member 35, and
the projecting units 36a, 36b, all preferably comprise aluminum
alloy. Further, in order to prevent electrical short circuits from
the piezoelectric member 13 to the projecting units 36a, 36b, the
contact portions with the piezoelectric member 13 are resin
coated.
Moreover, in accordance with the first embodiment of the invention,
the restricting pins 34a, 34b and the compression support member 35
are formed with a clearance. However, these elements may be fitted
so that the restricting pins 34a, 34b and the compression support
member 35 do not have a clearance. Moreover, the restricting pins
34a, 34b, the compression support member 35, and the projecting
units 36a, 36b may be integrally formed. By simplifying the
structure of the compression support member 32, the manufacturing
cost of the compression support member 32 can be reduced.
Furthermore, a blind hole, which is a mounting hole for the first
compression generating member, may be disposed in the compression
support member 35 in the center of the flat surface on the side
opposite to the vibration element 11. A coil spring 33, which is a
first compression generating member, is mounted between the
mounting hole 38 of the first compression generating member and the
roof surface of the casing 41. A spring force exerted by the coil
spring 33 urges the compression support member 35 toward the
vibration element 11. The urging force of the coil spring 33 and
compression support member 35 causes the ends of the projecting
units 36a, 36b disposed on the vibration element 11 side of the
compression support member 35 to contact the vibration element
11.
In the above-described manner, the compression support mechanism 31
in accordance with the first embodiment of the present invention
also functions as a fixed member to fix the vibration element 11 to
the casing 41.
Moreover, in accordance with the first embodiment of the present
invention, the compression support mechanism 31 comprises a first
compression force generating member, which is preferably the coil
spring 33 mounted between the compression support member 35 and the
roof of the casing 41. Because of this arrangement, enlargement in
size of the compression force generating member, which is an
accessory of the ultrasonic actuator 10 of the first embodiment,
can be suppressed as much as possible.
Moreover, in accordance with the first embodiment of the present
invention, the compression support mechanism 31 includes the
restricting pins 34a, 34b passing through and, in addition,
includes the compression support member 35 on the side opposite to
the side where the relative motion member 22 is located with
respect to the vibration element 11 having projecting units 36a,
36b on both sides with respect to the direction of relative motion.
Accordingly, the restricting pins 34a, 34b and the projecting units
36a, 36b are arranged with a simple structure, assembly is
simplified, and simplification and size reduction of the
compression support mechanism 31 are achieved. Moreover, support of
the vibration element 11 and compression of the vibration element
11 onto the relative motion member 22 can be performed
together.
Furthermore, in accordance with the first embodiment of the present
invention, the compression support mechanism 31, as described
hereinabove, has a very simple structure in which the compression
support member 32 and the compression generating member 33 are
assembled in a compact manner. Because of this, size reduction of
the ultrasonic actuator 10 can be achieved. Moreover, the
manufacturing cost can be reduced as much as possible.
In the above manner, the vibration element 11 is restricted in the
vibration direction (the up and down direction in FIG. 1A) of the
fourth order bending vibration B4, which is the second vibration,
by the projecting units 36a, 36b disposed in the compression
support member 35.
The casing 41, which comprises a base member, is a box-like
receiving member including an assembly comprising an upper casing
41a and a lower casing 41b. The casing 41 includes aperture units
43a, 43b for the relative motion member 22 to pass through.
The restricting pins 34a, 34b are perpendicularly fixed in a roof
surface of the upper casing 41a, facing toward the lower casing
41b. Moreover, as described above, six (6) conveyor rollers,
including the conveyor rollers 23a, 23b, are located and freely
rotatable in a predetermined position in the interior of the lower
casing 41b. Furthermore, interference cushioning material 44, such
as rubber, is mounted on the respective end surfaces of the upper
casing 41a and the lower casing 41b, which border on the aperture
units 43a, 43b.
A screw mechanism 45 is screw fixed in a portion of a roof plate of
the upper casing 41a contacted by the coil spring 33. In a state in
which the coil spring 33 contacts the screw mechanism 45, by
changing the screw set position of the screw mechanism 45 with
respect to the upper casing 41a, the length of the coil spring 33
is changed. The compressive force between the vibration element 11
and the relative motion member 22 is freely adjusted by adjusting
the set position of the screw mechanism 45, thereby adjusting of
the spring force generated by the coil spring 33.
In accordance with the first embodiment of the present invention,
the casing 41 maintains and houses the vibration element 11 and
compression support mechanism 31, in a manner such that the
compression of the vibration element 11 to the relative motion
member 22, and the movement of the relative motion member 22, is
performed very simply and in a small space.
The ultrasonic actuator 10 in accordance with the first embodiment
of the present invention is assembled according to the following
operations.
(1) The relative motion member 22 is loaded on the six (6) conveyor
rollers, including the conveyor rollers 23a, 23b, supported for
free rotation in the lower casing 41b.
(2) The coil spring 33 is mounted in the first compression force
generating member mounting hole 38 in the compression support
member 35. The restricting pins 34a, 34b are then fixed
perpendicularly to the roof surface of the upper casing 41a mount
the compression support member 35 in the upper casing 41a to
respectively pass through the through holes 37a, 37b in the
compression support member 35.
(3) The restricting pins 34a, 34b, which pass through the through
holes 37a, 37b, mount the vibration element 11 to the upper casing
41a such that the notches 11a, 11b in the vibration element 11 have
a clearance.
(4) In a state in which the compression support member 35 and
vibration element 11 are mounted in the upper casing 41a, as
described in the above paragraphs (2) and (3), the upper casing 41a
is placed on the lower casing 41b, and the upper casing 41a and the
lower casing 41b are fixed by suitable means.
The conditions when driving the ultrasonic actuator 10 assembled in
the above manner, will now be described below.
The A phase drive signal is input via lead wires 16a, 16c, and the
B phase drive signal is input via lead wires 16b, 16d, to the
vibration element 11. Thereupon, the vibration element 11
simultaneously generates a longitudinal vibration L1 which vibrates
in a direction corresponding to the direction of relative motion,
and a fourth order bending vibration B4 which vibrates in the
direction of compression.
At this time, the bending vibration B4 causes the relative motion
member 22 to receive pressure in its thickness direction from the
vibration element 11, specifically, pressure in the compression
direction. Because of the pressure received by the relative motion
member 22, the restricting pins 34a, 34b fit in the notches 11a,
11b, centered on the notches 11a, 11b, and a couple arises as both
ends in the length direction rise and fall in mutually opposite
directions.
However, in accordance with the first embodiment of the invention,
because the two (2) projecting units 36a, 36b are spaced apart in
the length direction of the vibration element 11, and contact the
vibration element 11, the projecting units 36a, 36b restrict the
vibration element 11 in the vibration direction of the bending
vibration B4. Moreover, because the restricting pins 34a, 34b
couple to the vibration element 11 via the notches 11a, 11b, the
restricting pins 34a, 34b restrict the vibration element 11 in the
vibration direction of the longitudinal vibration L1. Because of
this, the occurrence of a pitching vibration in the vibration
element 11 is accurately suppressed or eliminated.
In particular, in accordance with the first embodiment of the
invention, because the projecting units 36a, 36b contact the
vibration element 11 in two places corresponding to the nodes n2,
n4 of the fourth order bending vibration B4, the bending vibration
B4 arising in the vibration element 11 is attenuated as little as
possible, and the clutch effect of the bending vibration B4 can
operate effectively. Accordingly, the drive force generated by the
vibration element 11 can be efficiently transmitted to the relative
motion member 22, and the drive force or driving efficiency of the
ultrasonic actuator 10 can be increased.
Moreover, in accordance with the first embodiment of the invention,
because the projecting units 36a, 36b restrict the vibration
element 11 in the vibration direction of bending vibration B4 and
simultaneously perform compression of the vibration element 11 to
the relative motion member 22, it is not necessary to provide a
member exclusively for compression purposes. In this manner, a
complicated or bulky compression member is prevented.
Furthermore, in accordance with the first embodiment of the present
invention, vibration attenuation with respect to longitudinal
vibration L1 accompanying compression is larger than the prior art
examples shown in FIGS. 22 and 23. Further, in accordance with the
first embodiment of the invention, the suppression or elimination
of pitching vibration, the suppression of a reduction of driving
efficiency, and the suppression of the respective vibration
attenuation of the longitudinal vibration L1 and the bending
vibration B4 accompanying compression, can be balanced at a high
level. Because of this, in accordance with the first embodiment of
the invention, the performance of the ultrasonic actuator 10 as a
whole can be markedly increased.
For example, if the vibration attenuation accompanying compression
is taken into account, it is most advantageous to suppress pitching
vibration by compressing the endmost portions of the vibration
element 11 length direction with the projecting units 36a, 36b.
However, because the endmost portion is a position at which the
amplitude of the longitudinal vibration L1 is large, there is
concern regarding the vibration attenuation of the longitudinal
vibration L1. The compression position of the present embodiment is
of the invention set taking such vibration attenuation
comprehensively into account.
Second Preferred Embodiment
A vibration actuator in accordance with a second preferred
embodiment of the present invention will now be described below
with reference to the accompanying drawings. Furthermore, elements
which are the same as or similar to those described with respect to
the first embodiment are referred to by the same reference symbols,
and a detailed description of these like elements will not be
repeated here.
FIG. 5 is a diagram illustrating a ultrasonic actuator 10-1 and an
example of a waveform generated by the vibrations L1, B4. A
difference between the first embodiment and the second embodiment
is the structure of the compression support member 35-1 and
components in the neighborhood thereof, and the form of the
compression support member 35-1.
In accordance with the second embodiment of the present invention,
one end of a thin, laminar coupling member 50 is fixed to the upper
surface of the compression support member 35-1. The coupling member
50 is extended in the direction of relative motion, and is fixed to
the upper surface of the compression support member 35-1 via screws
51a, 51b. Another end of the coupling member 50 is tightly fixed by
a screw 54 to a lower surface of a bracket 53 which is tightly
fixed by screws 52a, 52b to a corner portion of the roof plate of
the upper casing 41a. Moreover, the coil spring 33 is mounted in an
interposed state between the upper surface of the coupling member
50 and the roof surface of the upper casing 41a.
Furthermore, in accordance with the second embodiment, the
restricting pins 34a, 34b are fixed perpendicularly in the lower
surface of the compression support member 35-1, and fit with
clearance into the notches 11a, 11b of the vibration element
11.
Other than the above-described details, the construction of the
ultrasonic 10-1 in accordance with the second embodiment of the
present invention is the same as that of the ultrasonic actuator 10
described with respect to the first embodiment of the present
invention.
In accordance with the second embodiment of the present invention,
because the compression support member 35-1 is fixed to the upper
casing 41 via the coupling member 50, the accuracy with which the
compression support member 35-1 restricts in the corresponding
motion direction of the vibration element 11 is greater than that
of the first embodiment. Moreover, because the restricting pins
34a, 34b are fixed in the compression support member 35-1, the play
between the restricting pins 34a, 34b and the compression support
member 35 which exists in accordance with the first embodiment does
not exist in the second embodiment. Because of this, the
restricting action in the direction of relative motion of the
vibration element 11 by the compression support member 35-1
increases. Accordingly, the driving efficiency and drive force of
the ultrasonic actuator 10-1 are greater than those of the first
embodiment.
Moreover, because the coupling member 50 comprises a thin, laminar,
elastic member, the coupling member 50 deforms flexurally centered
on the fixing position by the bracket 53. Because of this, the
compression support member 35-1 can deform minutely in an about
rectilinear form in the direction of compression. Therefore, in
accordance with the second embodiment of the present invention, the
generation of a pitching vibration in the vibration element 11 can
be reliably suppressed or eliminated in a manner similar to the
first embodiment.
Third Preferred Embodiment
In accordance with the first and second embodiments of the present
invention, the restricting pins 34a, 34b, and compression support
member 35 or 35-1, and projecting units 36a, 36b, all of aluminum
alloy. In contrast to these, in accordance with the third
embodiment of the present invention, these members comprise
methacrylic resin obtained by the polymerization of a methacrylic
acid ester.
More specifically, as shown in FIGS. 1.5, because the positions at
which the projecting units 36a, 36b come into contact with the
vibration element 11 are nodes of the bending vibration B4, the
bending vibration B4 is not attenuated by the projecting units 36a,
36b. However, these contact positions are greatly displaced from
the node n3 of the longitudinal vibration L1, and the projecting
units 36a, 36b cause attenuation of the longitudinal vibration L1.
Accordingly, in order to attenuate the longitudinal vibration L1 as
little as possible, it is desirable that the projecting units 36a,
36b comprise a material whose frictional force with the contacting
vibration element 11 is as small as possible. Moreover, it is
desirable that the projecting units 36a, 36b comprise a material
having a high vibration attenuating power, in order to cause
attenuation of pitching vibrations occurring in the vibration
element 11.
In accordance with the third embodiment of the invention, in the
above-described manner, methacrylic resin is selected as a material
having low frictional force with respect to the vibration element
11 and also large vibration attenuating power. Accordingly, even
when compressing the compression support member 35, 35-1 comprising
of methacrylic resin with the coil spring 33, the deformation
arising in the compression support member 35, 35-1 is small.
Because the deformation of the support member 35, 35-1 is small,
the compressive force can be reliably transmitted to the vibration
element 11 via the projecting units 36a, 36b, and the vibration
element 11 can be reliably restricted in the vibration direction of
the bending vibration B4.
Moreover, the projecting units 36a, 36b comprising methacrylic
resin have good contact slip with respect to the vibration element
11, and can make the vibration attenuation of the longitudinal
vibration L1 as small as possible.
Furthermore, because resin materials such as methacrylic resin have
high vibration attenuating power in comparison with metallic
materials, it becomes fundamentally difficult to generate pitching
vibrations. Accordingly, the clutch mechanism of the bending
vibration B4 can operate effectively, and the drive force generated
by the vibration element 11 can be transmitted efficiently to the
relative motion member 22. Because of this, the drive force and
driving efficiency of the ultrasonic actuator 10 are increased.
Furthermore, other than methacrylic resins, the projecting units
36a, 36b may comprise (1) thermosetting phenolic resins
(phenol-formaldehyde) obtained by the condensation reaction of
phenols and aldehydes, (2) polyamide resins, nylon-6 from the
polymerization of .epsilon.-caprolactam, nylon 66, the condensation
product of adipic acid and hexamethylene diamine, and the like, (3)
polytetrafluoroethylene (PTFE), fluoroethylene-propylene (FEP) and
the like fluoro resins, (4) polyacetal resins, (5)
acrylonitrile-butadiene copolymer resins (ABS resins), (6)
polyimide resins, which are polycondensates derived from
pyromellitic acid dianhydride and aromatic diamines, (7)
polyethylene resins, which are thermoplastics obtained by the
polymerization of ethylene, (8) polyvinyl chloride (PVC),
polycarbonate resins, which are polymers derived from the direct
reaction of phosgene with aromatic and aliphatic dihydroxy
compounds, or by ester interchange reactions with phosgene
derivatives, (10) polypropylene resins, which are thermoplastics
obtained by the polymerization of polypropylene using suitable
solvents, (11) polystyrene resins, which are thermoplastics
obtained by the polymerization of styrene, (12) epoxy resins, which
are thermosetting resins obtained by causing the condensation of
epoxy compounds with compounds which have active hydrogen atoms.
The above materials are as examples, and may be used singly or in
combination. Similar effects to those with methacrylic resins are
obtained with any of the above resins.
Moreover, it is not necessary for the restricting pins 34a, 34b,
compression support member 35, 35-1, and projecting units 36a, 36b
to all respectively comprise the above materials, and the above
materials may be used in only those portions which come into
contact with the vibration element 11.
Fourth Preferred Embodiment
FIG. 6 is a front view of an ultrasonic actuator 10-2 in accordance
with a fourth preferred embodiment of the present invention. FIG. 7
is a cross sectional diagram of a compression support mechanism in
a cross section VII--VII of FIG. 6.
As shown in FIG. 6, the ultrasonic actuator 10-2 in accordance with
the fourth embodiment of the invention includes a vibration element
11 to generate a first order longitudinal vibration L1, which is a
first vibration and a fourth order bending vibration B4, which is a
second vibration; a relative motion member 22-1, which is a rotary
member; a compression support mechanism 31-1; a compressive force
generation unit 33-1; and a casing 41-1, which houses the vibration
element 11 and a compression support mechanism 32-1 and in addition
supports the relative motion member 22-1 for free rotation. The
above elements are described in detail hereinbelow with reference
to FIGS. 6 and 7.
The vibration element 11 in accordance with the sixth embodiment of
the present invention is the same as the vibration element 11
described with respect to the first through third embodiments, and
a detailed description of the vibration element 11 will not be
repeated here.
The vibration element 11 includes an elastic member 12 having a
rectangular plate form, a piezoelectric member 13 mounted on one
flat side of the elastic member 12, and two drive force output
members 12a, 12b respectively comprising two sliding members. A
first order longitudinal vibration L1 and a fourth order bending
vibration B4 are generated in the vibration element 11 in
accordance with input drive signals. An elliptical motion, which is
the combination of the longitudinal vibration L1 and the bending
vibration B4, is thereby generated at the end surfaces of the drive
force output members 12a, 12b.
In accordance with the fourth embodiment, one side of the vibration
element 11 is disposed in the bottom portion 41-1a of the casing
41-1, and is supported and compressively brought into contact by a
fixed member 60, which is a third restriction member. Moreover, an
end surface of one side drive force output member 12a among the
drive force output members 12a, 12b is compressively contacted by
the outer circumferential face of the relative motion member 22-1,
which is described in more detail hereinafter. Furthermore, the
other drive force output member 12b does not come into contact with
another member, and drive force is not transmitted here.
The fixed member 60 corresponds to a nodal position n5 of the
outside of the bending vibration B4 generated in the vibration
element 11, and can suppress the vibration attenuation of the
bending vibration B4. However, because the fixed member 60 is
separated from the nodal position n3 of the longitudinal vibration
L1 generated in the vibration element 11, the fixed member 60 is a
primary factor in causing attenuation of the longitudinal vibration
L1. Accordingly, in order for the restricting pins 34a, 34b, the
compression support member 35 or 35-1, and the projecting units
36a, 36b, to not attenuate the longitudinal vibration as much as
possible, in a manner similar to the third embodiment, it is
desirable that the material of the fixed member 60 is such that the
frictional force with respect to the vibration element 11 is as
small as possible. Moreover, when a material having high vibration
attenuation is used, the pitching vibration which arises in the
vibration element 11 can be attenuated. Consequently, in accordance
with the fourth embodiment of the invention, the fixed member 60 is
formed of polyacetal resin. By forming the fixed member of
polyacetal resin, the contact slip between the vibration element 11
and the fixed member 60 is good, and the attenuation of the
longitudinal vibration L1 can be kept to a minimum.
Furthermore, the fixed member 60 can be formed of materials other
than polyacetal resin. For example, the fixed member can be
respectively formed of each of the materials disclosed in
accordance with the third embodiment, and results similar to those
obtained with polyacetal resin can be obtained with these
materials. For example, the fixed member 60 may comprise
methacrylic resin, phenolic resin, nylon-6 or nylon-66 polyamide
resins, PTFE or FEP fluoro resins, ABS resin, polyimide resin,
polyethylene resin, PVC, polycarbonate resin, polypropylene resin,
polystyrene resin, epoxy resin, and the like.
Moreover, in FIGS. 6 and 7, the electrode plates, lead wires, and
the like elements in the vibration element 11 have been omitted in
order to simplify the figures and the description.
The relative motion member 22-1 in accordance with the fourth
embodiment of the invention is a roller, supported to rotate freely
with the shaft support unit 61 as center, disposed in the bottom
portion 41-1a of the casing 41-1. As described above, the outer
circumference of the relative motion member 22-1 is in compressive
contact with the end face of the drive force output member 12a
disposed in the vibration element 11. Accordingly, when drive
signals are input to the vibration element 11, the relative motion
member 22-1 is rotationally driven in one direction, centered on
the shaft support unit 61.
As shown in FIGS. 6 and 7, in accordance with the fourth embodiment
of the invention, the compression support mechanism 31-1 comprises
a compression support member 32-1 which performs restriction of the
vibration element 11, a compression force generating member 33-1
which urges the vibration element 11 toward the relative motion
member 22-1, a compression support mechanism frame 62 which houses
the compression support member 32-1 and the compression force
generating member 33-1. The compression support mechanism 31-1
elements will be described in detail hereinbelow.
FIG. 8 is a diagram illustrating the compression support member
32-1 in accordance with the fourth embodiment of the invention.
More particularly, FIG. 8A is a front view of the compression
support member 32-1, and FIG. 8B is a lower surface view of the
compression support member 32-1.
The compression support member 32-1 comprises, integrally formed, a
compression support unit 32-1a, and two (2) coupling members 32-1b
disposed in one end of the length direction of the compression
support unit 32-1a, and a fixed unit 32-1c which is disposed in the
two (2) coupling members 32-1b.
The compression support unit 32-1a has a rectangular plate form.
Projecting units 36a, 36b are disposed perpendicularly in the
neighborhood of both end surfaces of a flat face in the length
direction of the compression support unit 32-1a. Moreover,
restricting pins 34a, 34b are disposed in the center portion of the
length direction of the flat face, fitting with clearance in the
notches 11a, 11b in the vibration element 11. The arrangement
positions of the projecting units 36a, 36b and the restricting pins
34a, 34b are the same as described above with respect to the second
embodiment of the invention as regards dimensions, function,
etc.
The coupling member 32-1b has a laminar form, similarly to the
coupling member 50 described with respect to the second embodiment,
and can undergo bending deformation centered on the fixed member
32-1c. Accordingly, the compression support unit 32-1a is able to
minutely deform in the compression direction in an about
rectilinear manner. Moreover, the fixed unit 32-1c is a fixed unit
when the compression support member 32-1 is fixed to the casing
41-1.
The compression force generation member 33-1 in accordance with the
fourth embodiment of the invention comprises a coil spring 33-1a,
which is a first compressive force generation member, and coil
springs 33-1b and 33-1c, which are second compressive force
generation members.
The coil spring 33-1a has one end mounted on a roof surface of the
compression support mechanism frame 62. The other end of the coil
spring 33-1a is disposed in a compression force transmission member
63. The roof surface, which is the mounting portion of the coil
spring 33-1a, is a screw setting screw mechanism (not shown in the
drawing). By changing the screw stop position of the screw
mechanism, the spring force generated by the coil spring 33-1a
generates can be changed. The spring force generated by the coil
spring 33-1a urges a spherical compression unit 64 disposed in the
compression force transmission member 63 toward the vibration
element 11.
On the other hand, the coil springs 33-1b and 33-1c each have one
end fixed to the bottom surface of the compression support
mechanism frame 62. The respective other ends of the coil springs
33-1b and 33-1c are in contact with the vibration element 11. The
vibration element 11 is urged toward the compression support member
32-1 by the spring force generated by the coil springs 33-1b and
33-1c.
In accordance with the fourth embodiment of the present invention,
by this means, the vibration element 11 is restricted in the
vibration direction of the longitudinal vibration L1, and, in
addition, the vibration element 11 is restricted in the vibration
direction of the bending vibration B4.
Furthermore, grounding of the piezoelectric member 13 disposed on
the vibration element 11 to the compression support mechanism frame
62 is performed via the coil spring 33-1b and the coil spring
33-1c.
As shown in FIGS. 6 and 7, in accordance with the fourth embodiment
of the present invention, the compression support member 32-1 and
the compression force generation member 33-1 are together housed by
the compression support mechanism frame 62 which has a
cross-sectional shape of a groove form.
A molded body 66 having concave portions 65a, 65b and 65c is
mounted in the interior of the compression support mechanism frame
62. The coil springs 33-1a, 33-1b and 33-1c are housed in
predetermined positions in the respective concave portions 65a, 65b
and 65c. The compression support member 32-1 and the vibration
element 11 are arranged between the coil spring 33-1a and the coil
springs 33-1b and 33-1c.
In accordance with the fourth embodiment of the invention, because
the vibration element 11, the compression support member 32-1, and
the compressive force generating member 33-1 are assembled as a
unit, using the compression support mechanism frame 62, it is
unnecessary to mount the vibration element 11, the compression
support member 32-1, and the compression force generating support
member 33-1 separately in the casing 41-1. Because of this, the
compression support mechanism frame 62 which houses the vibration
element 11, compression support member 32-1 and compressive force
generating mechanism frame 62 may be mounted to the casing 41-1. In
the above-described manner, the ease of assembly of the ultrasonic
actuator 10-2 is markedly improved.
In accordance with the fourth embodiment of the present invention,
the casing 41-1 comprises a bottom casing 41-1a and a roof plate
41-1b. Specifically, a roof plate fixing unit 67 and a fixing
member fixing unit 68 are disposed in the bottom plate 41a, at both
ends of the relative motion direction.
Moreover, the roof plate 41-1b is fixed by suitable means to the
roof plate fixing unit 67. In a predetermined position of the roof
plate 41-1b, the fixing unit 32-1c of the compression support
member 32-1 is fixed to the compression support mechanism frame
62.
As shown in FIG. 7 in order for the end of the roof plate 41-1b to
prevent interference of the coil spring 33-1a and the molded body
66 loaded in the compression support mechanism frame 62, the end of
the roof plate 41 is divided into two divided portions 41-1c. The
compression support mechanism frame 62 is supported by the divided
portions 41-1c.
The ultrasonic actuator 10-2 in accordance with the fourth
embodiment of the present invention is assembled by the following
operations (1)-(3).
(1) In a state in which the restricting pins 34a, 34b of the
compression support member 32-1 are fitted into the notches 11a,
11b of the vibration element 11, the compression support mechanism
31-1 is constituted by housing the compression support member 32-1
and compression force generating member 33-1 as a unit in the
compression support mechanism frame 62.
(2) By fitting the two divided portions 41-1c of the roof plate
41-1b into predetermined portions of the compression support
mechanism frame 62, the compression support mechanism 31-1 is fixed
in the roof plate 41-1b via the fixing member 32-1c of the
compression support member 32-1.
(3) The roof plate 41-1b, which fixes the compression support
mechanism 31-1, is fixed in the bottom plate 41-1a which shaft 61
supports the relative motion member 22-1.
In the above-described manner, in accordance with the fourth
embodiment of the present invention, because the compression
support member 32-1, the compression force generating member 33-1,
and the vibration element 11 are formed as a unit by the
compression support mechanism frame 62, the ease of assembly of the
ultrasonic actuator 10-2 is markedly increased.
Moreover, in accordance with the fourth embodiment of the present
invention, the form of the compression support member 32-1 is
simplified in comparison with that of the first through third
embodiments. Accordingly, the driving efficiency and drive force of
the ultrasonic actuator 10-2 is increased. Moreover, the ultrasonic
actuator 10-2 can be manufactured inexpensively.
Fifth Preferred Embodiment
FIG. 9 is an illustrative diagram of the ultrasonic actuator 10-3
in accordance with a fifth preferred embodiment of the present
invention. More particularly, FIG. 9A is a diagram illustrating the
ultrasonic actuator 10-3 and an example of a generated vibration
waveform. FIG. 9B is a top view of a vibration element 11 of the
ultrasonic actuator 10-3. Moreover, FIG. 10 is a perspective view
of the ultrasonic actuator 10-3 in accordance with the fifth
embodiment of the present invention.
As shown in FIGS. 9 and 10, the ultrasonic actuator 10-3 in
accordance with the fifth embodiment includes a vibration element
11, a relative motion member 22, a compression support mechanism
31-2, and a casing 41 which maintains the vibration element 11 and
the compression support mechanism 31-2, and through which the
relative motion member 22 passes. Among these elements, the
vibration element 11, the relative motion member 22 and the casing
41, are the same as the first embodiment of the invention, and are
referred to by the same reference symbols, and a detail description
of these elements will not be repeated.
Compression support mechanism 31-2
As shown in FIGS. 9 and 10, the compression support mechanism 31-2
in accordance with the fifth embodiment of the present invention,
includes a compression support member 32-2 which presents a
longitudinal cross section having the form of a groove, and a coil
spring 33, which is a first compression force generating member,
mounted in about the center of the upper surface of the compression
support member 32-2.
Projecting units 36a, 36b are formed in both ends of the length
direction of the compression support member 32-2, protruding in the
direction of the vibration element 11, which comprise a second
restriction member. The vibration element 11 is compressed toward
the relative motion member 22 by the projecting units 36a, 36b.
As shown in FIG. 9A, the projecting units 36a, 36b are formed,
relative to the corresponding direction of motion, in a position
more toward the ends of the vibration element 11 than the drive
force output members 12a, 12b. More particularly, in accordance
with the fifth embodiment of the invention, the projecting units
36a, 36b are positioned to coincide with the nodal positions n1, n5
of the fourth order bending vibration B4. By positioning the
projecting units 36a, 36b to coincide with the nodal positions n1,
n2, the vibration of the bending vibration B4 is not attenuated
accompanying the compression of the vibration element 11 by the
projecting units 36a, 36b. Furthermore, the projecting units 36a,
36b may be disposed in the neighborhood of the nodal positions n1,
n5 of the bending vibration B4, with a decrease, to some degree, of
the vibration attenuation effect.
Moreover, vibration absorbing materials 39a, 39b comprising, for
example, felt, or the like material which easily absorbs vibration,
are affixed in the contact surface of the projecting units 36a, 36b
with the vibration element 11. The vibration absorbing material
39a, 39b prevents the generation of noise due to the projecting
units 36a, 36b coming into contact with the vibration element 11.
Furthermore, even if the vibration absorbing materials 39a, 39b are
not disposed, the whole compression support member 32-2 may be
formed by the vibration absorbing material.
Furthermore, in a manner similar to the third embodiment, the whole
compression support member 32-2 including the projecting units 36a,
36b, for example, may be formed of one or more of polyacetal resin,
methacrylic resin, phenolic resin, polyamide resin, fluoro resin,
ABS resin, polyimide resin, polyethylene resin, PVC, polycarbonate
resin, polypropylene resin, polystyrene resin, and epoxy resin.
A mounting hole 38, through which the coil spring 33 does not pass,
is disposed in the center portion of the flat surface of the
compression support member 32-2 on the side opposite to the
vibration element 11. The coil spring 33 is mounted in the coil
spring mounting hole 38. A compressive force is generated by the
coil spring 33 and compresses the vibration element 11 toward the
relative motion member 22. The generated compression force is
transmitted to the vibration element 11 via the compression support
member 32-2.
Furthermore, the restricting pins 34a, 34b pass through through
holes 37a, 37b in the compression support member 32-2 fixed in the
casing 41. The restricting pins 34a, 34b which pass through the
through holes 37a, 37b fit with clearance into semicircular concave
portions 11a, 11b having a notch form in both sides of the center
of the length direction of the vibration element 11. Accordingly,
the vibration element 11 can move freely in the compression
direction, and is restricted having clearance with respect to the
direction of relative motion.
The operation of driving the ultrasonic actuator 10-3 in accordance
with the fifth embodiment of the present invention will now be
described below.
The vibration element 11 generates relative motion with respect to
the relative motion member 22, and a compressive force is generated
from the vibration element 11 toward the relative motion member 22
as a result of the bending vibration B4 generated in the drive
force output members 12a, 12b. A reaction force to the generated
compressive force causes a couple to be generated which causes the
two ends of the vibration element 11 in the length direction to
rise and fall in mutually opposite directions, centered on the
restricting pins 34a, 34b in the vibration element 11, as shown in
FIG. 9A.
In accordance with the fifth embodiment of the invention, to
compress with the projecting units 36a, 36b of the compression
support member 32-2 the end portions in the length direction of the
vibration element 11 by the drive force output members 12a, 12b,
the couple can be more effectively suppressed than in the first
through fourth embodiments. Therefore, the pitching vibration which
causes both end portions in the length direction of the vibration
element 11 to rise and fall in mutually opposite directions can be
reliably suppressed or eliminated.
In accordance with the fifth embodiment of the invention, the noise
due to the pitching vibration can be reduced. Moreover, the clutch
function performed by the bending vibration can operate
effectively, and the drive force of the vibration element 11 can be
transmitted with good efficiency to the relative motion member 22.
Therefore, in accordance with the fifth embodiment of the
invention, the drive force and driving efficiency of the ultrasonic
actuator 10-3 can be increased.
Moreover, in accordance with the fifth embodiment of the present
invention, because the compression of the vibration element 11
toward the relative motion member 22 is also performed by the
projecting units 36a, 36b, it is not necessary to provide a member
exclusively for compression purposes. In this manner, the
complication or bulkiness of the compression member are
prevented.
Furthermore, the fifth embodiment of the present invention provides
vibration attenuation accompanying compression with respect to the
longitudinal vibration L1 which is larger in comparison with the
prior art cases shown in FIGS. 22 and 23. However, by accordance
with the fifth embodiment of the invention, the suppression or
elimination of pitching vibration, and the suppression of a
reduction of driving efficiency, and the suppression of the
respective vibration attenuation of the longitudinal vibration L1
and the bending vibration B4 accompanying compression, can be
balanced at a high level. Therefore, in accordance with the fifth
embodiment, the performance of the ultrasonic actuator 10-3 as a
whole can be caused to markedly increase.
Sixth Preferred Embodiment
FIG. 11 is a diagram illustrating an ultrasonic actuator 10-4 and a
generated vibration waveform in accordance with a sixth preferred
embodiment of the present invention. Omitted portions of the
vibration actuator are the same as shown in FIG. 9A.
The sixth preferred embodiment differs from the fifth embodiment of
the invention in that coil springs 33-1, 33-2, respectively, are
used to compress the compression support member 32-3.
Coil spring mounting holes 38-1, 38-2 are disposed in the same
positions as the positions compressed by the projecting units 36a,
36b, and coinciding with the nodal positions n1, n5 of the bending
vibration B4. Further, the coil spring mounting holes 38-1, 38-2
are located in the compression support member 32-3 with respect to
the length direction more toward the vibration element 11 ends than
the drive force output members 12a, 12b of the vibration element
11.
Moreover, screw mechanisms 45-1, 45-2 are disposed in positions at
which the coil springs 33-1, 33-2 contact the upper casing 41a.
In accordance with the sixth embodiment of the present invention,
effects can be achieved which are the same as those described with
respect to the fifth embodiment. Furthermore, because two coil
springs 33-1, 33-2 are used, the pitching vibration accompanying
driving can be more reliably suppressed. Moreover, by independently
adjusting the compressive force generated by the coil springs 33-1,
33-2, left and right differences of drive force which accompany
rotations of the drive direction can also be adjusted.
Seventh Preferred Embodiment
FIG. 12 is a diagram illustrating an ultrasonic actuator 10-5 and
an example of a generated vibration waveform in accordance with a
seventh preferred embodiment of the present invention.
The seventh preferred embodiment is a modification of the sixth
embodiment, and differs from the sixth embodiment at least in that
the positions at which the drive force output members 12a, 12b are
formed are different.
In accordance with the seventh embodiment of the invention, the
drive force output members 12a, 12b are respectively located at
inner antinode positions of the bending vibration B4. Furthermore,
the compression position due to the projecting units 36a, 36b
coincides with the nodal positions n2, n4 of the bending vibration
B4, which are more toward the vibration member 11 ends than the
drive force output members 12a, 12b.
In accordance with the seventh embodiment of the present invention,
because the drive force output members 12a, 12b are located toward
the center in the length direction of the vibration element,
interference with amplitude components of the longitudinal
vibration L1 becomes small. However, because the distance between
the drive force output members 12a, 12b has become small, the
flatness of the drive force output members 12a, 12b can
increase.
Accordingly, driving efficiency increases, and a design is possible
which prevents the generation of noise originating because of
insufficient flatness of the drive force output members 12a, 12b.
Furthermore, because the drive force output members 12a, 12b are
brought close, manufacture in order to maintain flatness can be
simplified, and, the design can reduce the manufacturing cost.
Furthermore, as shown in FIG. 12, the compression positions by the
projecting units 36a, 36b may be located to coincide with the nodal
positions n1, n5 of the bending vibration B4, and the effect of
control of the pitching vibration can be further increased.
Eighth Preferred Embodiment
FIG. 13 is a perspective exploded view of an ultrasonic actuator
10-6 in accordance with an eighth preferred embodiment of the
present invention. Moreover, FIG. 14 is a front view of the
ultrasonic actuator 10-6 in accordance with the eighth embodiment;
FIG. 15 is a partially transparent front view of the ultrasonic
actuator 10-6 in accordance with the eighth embodiment; and FIG. 16
is a longitudinal sectional view in the center of the ultrasonic
actuator 10-6 in accordance with the eighth embodiment.
Furthermore, for convenience of description, the piezoelectric
member 13 and silver electrodes 15 are omitted from FIG. 13, and
the silver electrodes 15 are omitted from FIGS. 14-16.
As shown in FIGS. 13-16, the ultrasonic actuator 10-6 in accordance
with the eighth embodiment of the invention includes a vibration
element 11; a relative motion member 22; and a fixed member 70
comprising a support member 71 to support the vibration element 11,
a compression member 72 to compress the vibration element 11 toward
the relative motion member 22, and a base member to support the
fixed member 70.
The seventh embodiment of the present invention differs from the
previous embodiments in the support member 71, compression member
72, and base member 73. These differing portions are described in
detail hereinbelow.
FIG. 17 is a top view of a support member 71 in accordance with the
eighth preferred embodiment of the invention. As shown in FIGS.
13-17, the support member 71 includes an elastic plate 74 and a
support plate 75. The elastic plate 74 comprises an elastic
material, for example, a metallic material. As shown in FIG. 17,
the elastic plate 74 is thin and has an approximately rectangular
flat plate shape. The elastic plate 74 includes four support plate
mounting holes 76a-76d, and two (2) restricting pin mounting holes
77a, 77b, a piezoelectric member movement limiting hole 78, and two
mounting holes 79a, 79b to the base member. Moreover, U-shaped
notch portions 81a, 81b are disposed in about the centers of the
two side faces of the elastic plate 74.
On the other hand, the support plate 75 comprises, for example, a
metallic material, and is a plate member having adequate rigidity.
Four screw holes are disposed in the support plate 75 in positions
which coincide with the support plate mounting holes 76a-76d
disposed in the elastic plate 74. Moreover, a through hole is
disposed in the support plate 75 having the same diameter as, and
corresponding in position to, the compression member movement
limiting hole 78 in the elastic plate 74. Furthermore, the support
plate 75 includes through holes having the same diameter as, and
corresponding in position to, the restricting pin mounting holes
77a, 77b disposed in the elastic plate 74. The support plate 75 is
fixed to the elastic plate 74 by screw setting in the screw holes,
inserting screws 82a-82d in the support plate mounting holes
76a-76d, so as to be superposed coincident with the holes.
Moreover, as shown in the drawings, the restricting pins 34a, 34b
which are first restriction members, pass through through holes
disposed in the elastic plate 74 and support plate 75, and are
perpendicularly fixed, for example by welding, adhesion, or the
like suitable means. The restricting pins 34a, 34b extend toward
the vibration element 11. The restricting pins 34a, 34b are mounted
to the support plate 71 at a pitch about coinciding with the pitch
of the notches 11a, 11b disposed in the vibration element 11.
The support member 71 is fixed by mounting screws 83a, 83b which
pass through the mounting holes 79a, 79b, in the bottom surface of
an L-shaped block 87 which is disposed in the base member 73,
described in detail hereinafter. In the above-described manner,
elastic plate 74 acts as a plate spring.
Accordingly, the restricting pins 34a, 34b fixed to the support
member 71, the elastic plate 74 can minutely deform about
rectilinearly by bending in the direction in which the compressive
force acts which compresses the vibration element 11 toward the
relative motion member 22.
FIG. 18 is a four surface view of the compression member 72 in
accordance with the eighth embodiment of the present invention.
More particularly, FIG. 18A is a left side view, FIG. 18B is a
front view, FIG. 18C is a right side view, and FIG. 18(D) is a
lower surface view of the compression member 72. As shown in FIGS.
18A-18D, the compression member 72 is a rectangular
parallelepipedal box made of suitable material.
Furthermore, in a manner similar to the third embodiment, in
accordance with the eighth embodiment, the material of the
restricting pins 34a, 34b or compression member 72 which contacts
with the vibration element 11 may be formed of at least one of
materials such as methacrylic resin, phenolic resin, polyamide
resin, fluoro resin, polyacetal resin, ABS resin, polyimide resin,
polyethylene resin, PVC, polycarbonate resin, polypropylene resin,
polystyrene resin, and epoxy resin, which is desirable in order to
suppress, as much as possible, the vibration attenuation of the
vibration element 11.
Projecting units 84a-84d having semicylindrical form, which are
second restriction members, are disposed in the four corners of the
compression member 72. The projecting units 84a, 84c are positioned
to contact in positions which extend over the nodal position n2 of
the fourth order bending vibration B4 generated in the vibration
element 11. Moreover, the projecting units 84b, 84d are positioned
as to contact in positions which extend over the nodal position n4
of the fourth order bending vibration B4. In the above manner, the
vibration element 11 is reliably restricted in the vibration
direction of the bending vibration B4 by the projecting units
84a-84d. Furthermore, the contact positions of the projecting units
84a-84d are not necessarily as positions which exactly coincide
with the nodal positions n2, n4, but may be in the neighborhood of
the nodal positions n2, n4.
Claw members 85a-85d are disposed projecting toward the vibration
element 11 and outside the projecting units 84a-84d. The inner
faces of the claw members 85a-85d are in contact with the side
faces of the vibration element 11. The claw members 85a-85d
restrict the vibration element 11 in its amplitude direction.
In the above manner, in accordance with the eighth embodiment of
the invention, the vibration element 11 is restricted in the
vibration direction of the bending vibration B4 by the projecting
units 84a-84d which are disposed in the compression member 72.
Furthermore, the vibration element 11 is restricted in two
directions, specifically, the vibration direction of the bending
vibration B4 and the direction at right angles to the vibration
direction of the longitudinal vibration L1 and the vibration
direction of the bending vibration B4, by the claw members 85a-85d
disposed in the compression member 72.
A semicylindrical projecting unit 86 is disposed in about the
center of the compression member 72, facing the support member 71.
The projecting unit 86 has an external diameter smaller than the
compression member movement limiting hole 78 in the support member
71, and is inserted with clearance into the compression member
movement limiting hole 78. In accordance with the eighth embodiment
of the invention, a movement limiting mechanism is formed by the
projecting unit 86 disposed in the compression member 72, and the
compression member movement limiting hole 78 disposed in the
support member 71. The movement of the compression member 72 is
limited in the vibration direction of the longitudinal vibration L1
by the movement limiting mechanism.
As shown in FIGS. 14 and 15, in accordance with the eighth
embodiment of the invention, the restricting pins 34a, 34b are
joined by suitable means, for example, welding or adhesion, and the
like. In this manner, with the support member 71 in a state joined
to the vibration element 11, the compression member 72 is caused to
contact the vibration element 11 at a predetermined position.
Thereupon, as shown in FIG. 16, the projecting unit 86 passes
through the compression member movement limiting hole 79 in a state
having clearance. Accordingly, the movement of the compression
member 72 in the vibration direction of the longitudinal vibration
is limited by the support member 71.
During the movement of the compression member 72, the projecting
unit 84b and the claw member 85b pass through the U-shaped notch
unit 81a. Moreover, the projecting unit 84d and the claw member 85d
pass through the U-shaped notch unit 81b. Because a clearance
exists between the projecting unit 86 and the compression member
movement limiting hole 78, the compression member 72 displaces
minutely in the vibration direction of the longitudinal vibration.
However, because of this displacement, the projecting unit 84b and
the claw member 85b both do not make contact with the notch unit
81a. Moreover, the projecting unit 84d and the claw member 85d both
do not make contact with the U-shaped notch unit 81b. In the above
manner, the support member 71 and the compression member 72, as
shown in FIGS. 14-16, do not mutually interfere, and both the
support member 71 and the compression member 72 are arranged in a
displacement state with respect to the direction of the compressive
force acting to compress the vibration element 11 toward the
relative motion member 22.
In accordance with the eighth embodiment of the invention, the
vibration element 11 is supported without play by means of the
support member 71 via the restricting pins 34a, 34b, and moreover
the vibration element is urged toward the relative motion member 22
by the compression member 72.
The base member 73 is a housing member having a rectangular shape.
An L-shaped bracket 87 is fixed by a bolt 88 to the outer surface
of the base member 73. As described above, the support member 71 is
fixed to the bottom surface of the L-shaped bracket 86.
Moreover, an about cylindrical terminal 89 for compression use is
housed in the interior of the base member 73. The cylindrical
terminal 89 has a large diameter at one end, and with the large
diameter end exposed to the exterior. A coil spring 90, which is a
first compressive force generating member, is mounted on the
periphery of the small diameter portion of the cylindrical terminal
89. A compressive force adjustment screw 92 is screw set into the
base member 73 via a cylindrical spring length adjustment member 91
in the rear end of the coil spring 90.
The ultrasonic actuator 10-6 in accordance with the eighth
embodiment of the invention is assembled as shown in FIGS. 14-16,
the relative motion member 22, vibration element 11, support member
71, compression member 72 and base member 73 being placed as shown
in FIG. 13. During assembly, the end of the cylindrical terminal 89
is placed in contact in about the center of the upper surface of
the compression member 72. By adjusting the screwed-in position of
the compression adjustment screw 92, the spring force generated by
the coil spring 90 is adjusted, and the compressive force which is
transmitted to the compression member 72 via the compression
terminal 89 is adjusted.
In accordance with the eighth embodiment of the invention, the
support of the vibration element 11 by the support member 71, and
the compression of the vibration element 11 by the compression
member 72, can be performed by the fixed member 70 without mutual
interference between the support member 71 and the compression
member 72.
Moreover, in accordance with the eighth embodiment of the
invention, because it is not necessary to perform compression of
the vibration element 11 by the support member 71, the support
member 71 and the vibration element 11 can be brought into contact
by the fixed member 70. In this manner, the vibration element 11
can be compressed by the fixed member 70 with a desired compressive
force and without play toward the relative motion member 22.
Ninth Preferred Embodiment
In accordance with the ninth preferred embodiment of the present
invention, the respective forms of the support member 71 and
compression member 72 described with respect to the eighth
embodiment are altered.
FIG. 19 is a top view of the support member 71-1 in accordance with
the ninth embodiment of the invention. Moreover, FIGS. 20A-20D are
four surface views of the compression member 72-1 in accordance
with the ninth embodiment. Specifically, FIG. 20A is a left side
view, FIG. 20B is a front view, FIG. 20C is a right side view, and
FIG. 20D is a lower surface view of the support member 72-1 in
accordance with the ninth embodiment. Moreover, in the description
of FIGS. 19 and 20, portions which are the same as those in the
eighth embodiment shown in FIGS. 17 and 18 are referred to by the
same reference symbols, and detailed descriptions of the like
elements will not be repeated here.
The elastic plate 74-1 which comprises the support member 71-1 in
the ninth embodiment includes through holes 81a', 81b' instead of
the U-shaped notches 81a, 81b in the eighth embodiment. As shown in
FIG. 19, the through holes 81a', 81b' are formed in positions a
little inside of the edges of the elastic plate 74-1.
Moreover, the support member 71-1 in accordance with the ninth
embodiment include projecting units 84a-84d at positions a little
more inside than those in the eighth embodiment. The pitch of the
projecting units 84a and 84c, and the pitch of the projecting units
84b and 84d, together, is the same as the pitch of the through
holes 81a' and 81b'. In the accordance with the ninth embodiment of
the invention, the projecting unit 84b passes through the through
hole 81a' with clearance, and the projecting unit 84d passes
through the through hole 81b' with clearance.
Furthermore, the support member 72-1 in accordance with the ninth
embodiment does not include claw members 85b, 85d, and the
restriction of the vibration element 11 in the width direction is
performed by the claw members 85a, 85c.
In accordance with the ninth embodiment of the invention, about
similar effects can be obtained to those of the eighth embodiment
with a structure simpler than that of the eighth embodiment.
FIG. 21 is a partially transparent front view of an ultrasonic
actuator 10-7 in accordance with the tenth preferred embodiment of
the present invention. The ultrasonic actuator 10-7 in accordance
with the tenth embodiment differs from the ultrasonic actuator 10-6
of the eighth embodiment shown in FIGS. 13-16 in that the position
of contact on the upper surface of the vibration element 11 by the
projecting units 84a-84d disposed in the compression member 72 is
changed.
As shown in FIG. 21, in accordance with the tenth embodiment, the
projecting units 84a-84d are similar to the ultrasonic actuator
10-3 of the fifth embodiment shown in FIGS. 9 and 10, or to the
ultrasonic actuator 10-4 of the sixth embodiment shown in FIG. 11.
Contact with the upper surface of the vibration element 11 at the
vibration element end is more than the drive force output members
12a, 12b with respect to the direction of relative motion.
The position at which the projecting units 85a, 85c contact the
vibration element 11 is corresponds to an outer nodal position n1
of the bending vibration B4. The position at which the projecting
units 85b, 85d contact the vibration element 11 corresponds to an
outer nodal position n5 of the bending vibration B4.
Moreover, similarly to the ultrasonic actuator 10-6 of the eighth
embodiment, the drive force output members 12a, 12b are disposed in
antinode positions l1, l4 of the bending vibration B4.
Accordingly, the pitching motion in which the length direction end
portions of the vibration element 11 are caused to rise and fall in
mutually opposite directions can be reliably suppressed or
eliminated. Moreover, in accordance with the tenth embodiment, the
noise generation due to the pitching vibration can be reduced.
Moreover, the clutch function which is the role of the bending
vibration B4 can operate effectively, and by this means, the drive
force of the vibration element 11 can be efficiently transmitted to
the relative motion member 22. Accordingly, the ultrasonic actuator
10-7 in accordance with the tenth embodiment increases the drive
force and driving efficiency over those of the ultrasonic actuator
10-6 of the eighth embodiment.
In the descriptions of each embodiment, an ultrasonic motor has
been taken as an example of a vibration actuator. However, there is
no such limitation of the vibration actuator of the present
invention, and it can equally well be applied to vibration
actuators which use vibration regions other than the
ultrasonic.
Moreover, in accordance with embodiments of the present invention,
examples have been described with respect to vibration elements
using degenerate modes of different form, which cause the
generation of a first vibration which is a first order longitudinal
vibration, and a second vibration which is a fourth order bending
vibration. However, the present invention is not limited to a
vibration actuator using such modes, and vibration actuators which
generate other vibrations are equally suitable for application. For
example, the present invention is equally applicable to a vibration
actuator including a vibration element having degenerate modes of
different form, causing the generation of a first vibration which
is a first order longitudinal vibration, and a second vibration
which is a second order, sixth order, or eighth order bending
vibration.
Moreover, the present invention is also applicable to a vibration
actuator having a vibration element using the combination of other
than a longitudinal vibration and a bending vibration, to generate
a first vibration which vibrates in the direction of relative
motion, and a second vibration which vibrates in a direction
intersecting the direction of relative motion, and having an output
vibration element which outputs drive force from plural drive force
output members in the direction of relative motion. For example,
the present invention may be applied to a vibration actuator
including a vibration element having both an electromechanical
conversion element which generates vibration in the length
direction, and an electromechanical conversion element which
generates deformation in the elastic member thickness direction,
mounted in a laminated configuration in the elastic member end
side.
More particularly, the present invention generates a first
vibration which vibrates in the direction of relative motion, and a
second vibration which vibrates in a direction which intersects the
direction of relative motion and, by application to a vibration
actuator having a vibration element which generates an elliptical
motion in plural drive force output members which are located in
the direction of relative motion, suppresses or eliminates the
pitching vibration during driving of the vibration actuator,
suppresses a decrease of driving efficiency, and suppresses the
respective vibration attenuation of the first and second vibrations
which accompany compression, can cause balance at a high level, and
is desirable.
Moreover, the present invention is also applicable to a vibration
actuator having a first restriction member which restricts with
respect to the direction of vibration of the first vibration, and a
second restriction member which restricts the vibration element as
regards the vibration direction of the second vibration in at least
two places relating to the vibration direction of the first
vibration, the first restriction member and second restriction
member do not influence the respective location state. For example,
the first restriction member is not disposed in a compression
support member, and can for example be mounted directly in the roof
surface of the casing, or, intermediately via a screw.
Moreover, in accordance with embodiments of the present invention,
the second restriction member, is disposed in two places relating
to the vibration direction of the second vibration. However, the
present invention is not limited to this type of vibration
actuator, and the second restriction member may be disposed in
three or more places. For example, as shown in FIG. 1A, the second
restriction members are disposed in three places, the nodal
positions n2, n3 and n4.
Moreover, in accordance with embodiments of the present invention,
the first restriction members are fitted with play in notch units
disposed in center positions of both side surfaces of the length
direction of the vibration element. However, the present invention
is not limited to this type of first restriction member. For
example, the first restriction members may be fitted coupled to the
vibration element at positions other than these positions.
Moreover, in accordance with embodiments of the present invention,
the first restriction members are fitted into semicircular notches
disposed in the vibration element. However, the first restriction
member may be disposed in the vibration element and fitted in a
manner having a clearance.
Moreover, in the accordance with the first through seventh
embodiments of the invention, the projecting unit, which is a
second restriction member, supports using a compression support
member. However, the vibration actuator is not limited to this type
of projecting unit. For example, in a manner similar to the eighth
through tenth embodiments, the restricting pins and projecting
units may be supported without using a compression support
member.
Moreover, in accordance with embodiments of the present invention,
the first restriction member and the compression support member are
coupled in three states: (1) to fit in having clearance in the
compression support member, (2) to fit in having no clearance in
the compression support member, (3) fixed in the flat surface of
the vibration element side of the compression support member.
However, the coupling in the vibration actuator is not limited to
these three states, and fitting of the first restriction member
into the compression support member in other configurations is
likewise applicable.
Moreover, in accordance with the fifth through seventh embodiments,
an example was given of a projecting unit which compresses the
vibration element in the whole length of the width direction of the
vibration element. However, the vibration actuator is not limited
to compressing the vibration element in this manner, and
compression in a portion of the width direction of the vibration
element is equally applicable to the present invention.
Moreover, in accordance with the eighth embodiment of the present
invention, the vibration element 11 is compressed using a coil
spring 90 which is a first compressive force generating member.
However, the present invention is not limited to compressing the
vibration element in this manner, and the eighth embodiment may
include a second compression generation member together with the
coil spring 90, as described with respect to the fourth embodiment
shown in FIGS. 6-8.
Moreover, in accordance with the eighth embodiment of the
invention, the vibration element 11 was restricted using
restricting pins 34a, 34b, which are the first restriction members,
and projecting units 84a-84d which are the second restriction
members. However, the present invention is not limited to
restricting the vibration element in this manner. For example, the
eighth embodiment of the invention may include with restricting
pins 34a, 34b, and projecting units 84a-84d, together with third
restriction members, as described with respect to the fourth
embodiment shown in FIGS. 6-8.
Moreover, in accordance with the eighth embodiment of the
invention, the movement limiting mechanism limits the movement of
the compression member 72 in the vibration direction of the
longitudinal vibration by disposing the projecting unit 86 in the
compression member 72 and disposing the compression member movement
limiting hole 78 in the support member 71. However, the present
invention is not limited to such a configuration. For example, a
suitable movement limiting mechanism may be disposed in one of the
support member 71 and compression member 72.
Furthermore, in accordance with embodiments of the present
invention, the electro-mechanical conversion element is a
piezoelectric element. However, the present invention is not
limited to a vibration actuator using a piezoelectric element, and
any element which converts electrical energy into mechanical
element can equally well be applied. For example, an
electrostrictive element can be used instead of a piezoelectric
element.
In accordance with embodiments of the present invention, the
occurrence of a pitching vibration can be markedly suppressed, or
eliminated.
In accordance with embodiments of the present invention, the drive
force generated by the vibration element is not attenuated, as much
as possible.
In accordance with embodiments of the present invention, there is
no play between the first restriction member and the vibration
element.
In accordance with embodiments of the present invention, by
displaceably locating both the first and second restriction members
without mutual effects with respect to the direction of action of
the compressive force between the vibration element and the
relative motion member, the occurrence of a pitching vibration can
be markedly suppressed, or eliminated.
In accordance with embodiments of the present invention, the
compression member limits movement in the vibration direction of
the first vibration.
In accordance with embodiments of the present invention, the second
restriction member restricts the vibration element in two
directions, the vibration direction of the second vibration and a
direction which intersects the vibration direction of the first
vibration and the direction of vibration of the second
vibration.
In accordance with embodiments of the present invention, the
vibration element is supported freely displaceably in the
compression direction.
In accordance with embodiments of the present invention, a
compression support mechanism having a simplified design and
smaller size can be achieved.
In accordance with embodiments of the present invention, by urging
the vibration element in the direction of the relative motion
member, the occurrence of a pitching vibration can be markedly
suppressed, or eliminated.
In accordance with embodiments of the present invention, the
vibration generated by the vibration element is not attenuated to
as great an extent as possible.
In accordance with embodiments of the present invention, fine
adjustment of the compressive force of the first compressive force
generating member and the second compressive force generating
member can be easily and accurately performed.
In accordance with embodiments of the present invention, the
generation of pitching vibrations is markedly suppressed.
In accordance with embodiments of the present invention, a maximum
driving efficiency can be achieved.
Although a few preferred embodiments of the present invention have
been shown and described, it will be appreciated by those skilled
in the art that changes may be made in these embodiments without
departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
* * * * *